1. Field of the Invention
The present invention relates to an improvement in an inductor for noise reduction constructed by winding wire around a core member.
2. Description of the Prior Art
Conventionally, an inductor comprising a core member formed of a magnetic substance such as ferrite, and having flange portions at both ends and wire wound around a portion between the flange portions of this core member, has been widely used as an inductor for noise reduction.
In the inductor constructed as described above, a resonant point caused by stray capacitance or the like formed between turns of the wound wire exists at high frequencies. Thus, frequencies higher than the resonant point, the inductor acts like a capacitor rather than an inductor.
Accordingly, when the above described inductor is used as an inductor for noise reduction, the impedance rapidly changes in the vicinity of the resonant point, resulting in a phenomenon such as oscillation. Thus, there is a problem of being unable to effectively remove noise.
On the other hand, a construction has been known in which a resistor is connected in parallel with the inductor so as to restrain the above described phenomenon such as oscillation. When the resistor is connected, as a separate part, in parallel with the inductor, however, there are some problems. For example, manufacturing cost is increased and it is difficult to meet the requirement for miniaturization.